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Ca 2+ requirement for photosynthetic oxygen evolution of spinach and mangrove photosystem II membrane preparations
Author(s) -
Preston Christopher,
Critchley Christa
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)80630-x
Subject(s) - spinach , photosystem ii , thylakoid , oxygen evolution , avicennia marina , photosynthesis , photosystem i , chemistry , oxygen , photosystem , mangrove , biophysics , biochemistry , botany , biology , chloroplast , ecology , electrode , organic chemistry , electrochemistry , gene
CaCl 2 significantly increased the photosynthetic oxygen‐evolution activity of photosystem II membrane preparations isolated from spinach and the mangrove Avicennia marina , but not that of spinach thylakoids. This increase is composed of two parts; one due to Cl − , the other to Ca 2+ . Under Cl − ‐sufficient conditions photosystem II particle preparations required only 2 mM Ca 2+ for maximum oxygen evolution, irrespective of the presence of the 23‐ and 18‐kDa polypeptides. It is suggested that there is no immediate interaction between Ca 2+ and the 23‐ or 18‐kDa polypeptides and that instead Ca 2+ acts directly on the oxygen‐evolving centre, perhaps via another, as yet unidentified protein.